Enhanced optical and radiation protection characteristics of lead-free ZnO-enriched B2O3–TeO2–Na2O–Y2O3 glasses for advanced opto-shielding applications

Abstract

A novel series of ZnO-doped borate-based glasses with compositions (70.5-x)B₂O₃–20TeO₂–9Na₂O–0.5Y₂O₃–xZnO (x = 9, 12, 15, and 18 mol %) were synthesized using a rapid quenching method. Their optical and radiation shielding properties were thoroughly evaluated to assess the impact of ZnO incorporation. UV–Vis. absorption spectroscopy confirmed the amorphous nature of the glasses and showed a progressive blue shift in the absorption edge with increased ZnO, correlating with elevated optical band gap values (3.396 to 3.664 eV for direct and 2.553 to 3.196 eV for indirect transitions) due to enhanced bridging oxygens and fewer NBOs. The decrease in Urbach energy and refractive index indicated improved structural order and compactness. Optical parameters like molar refraction, polarizability, basicity, and electronegativity varied with composition, reflecting ZnO-induced structural changes. Zn18Y exhibited the highest transparency (81.6%) and the lowest reflection loss. Radiation attenuation factors and radiation protection efficiency (RPE) were computed, showing improved shielding with higher ZnO content, especially at low photon energies. Z_eff and RPE declined with energy but remained superior for Zn-rich glasses. Zn18Y demonstrated the best radiation shielding due to its high density. Comparisons with other glass systems confirmed the competitive radiation attenuation efficiency of the prepared glasses. The outcomes of the developed glasses show strong promise for transparent radiation protection applications.